Development and evaluation of a mobile health (mHealth) application for smoking cessation among adolescents in Indonesia: a mixed methods randomised controlled trial study protocol.

introductionAdolescent smoking poses a critical public health challenge in Indonesia, where approximately 7.4% of adolescents are current smokers. This issue is compounded by the tobacco industry's aggressive marketing strategies, particularly targeting youth. Mobile health (mHealth) interventions offer promising alternatives for smoking cessation because of their accessibility and adaptability. However, while mHealth applications have shown potential in promoting smoking cessation, their efficacy remains inconsistent, particularly among adolescent populations in low- and middle-income countries. This study aims to develop an innovative mHealth intervention model designed explicitly for adolescent users. METHODS AND ANALYSIS: This study used a mixed-methods, sequential, exploratory approach, including a randomised controlled trial. The research will be conducted in three phases: (1) a qualitative study to inform the app's design; (2) a development phase using the Rapid Application Development model; and (3) a single-blind, two-arm randomised controlled trial to evaluate the app's efficacy. Participants will be randomised into either the mHealth intervention group or a paper-based control group using block randomisation to ensure balanced allocation and minimise bias. The protocol is compliant with the Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) guidelines for transparency and reporting. The study population will consist of adolescent smokers aged 13-15 years who reside in Padang City. A total of 110 participants will be recruited, with 55 adolescents in the intervention group and 55 in the control group. The primary outcome is smoking abstinence at 1-, 3- and 6-month follow-ups, which will be assessed through a self-report questionnaire. Secondary outcomes include changes in self-efficacy, motivation, social support, nicotine dependence and user engagement with the intervention. ETHICS AND DISSEMINATION: The study complies with protocols, the Helsinki Declaration, the principles of Good Health Research Practice and regulatory requirements. The protocol was approved by the Medical and Health Research Ethics Committee, Faculty of Medicine, Public Health and Nursing, Gadjah Mada University (Ref No: KE-FK-0864-EC-2025). Informed consent will be obtained from both adolescents and their parents/guardians, ensuring confidentiality and voluntary participation. The results of this study will be published in peer-reviewed journals. TRIAL REGISTRATION NUMBER: NCT07198828.